Keeping hydrated is important for optimal sports performance. And for decades we’ve had that area covered by sports drinks. But are sports drinks really performance-enhancing, or are they mostly marketing spin when just plain old water will do the trick for most people? That’s what I’ll explore in today’s podcast along with giving you my personal DIY recipe for sports drink to get these drinks into you on the cheap.
The term ‘sports drink’ generally refers to drinks that contain carbohydrates and electrolytes in specific concentrations. The main ingredient of sports drinks is of course water which is there to help offset the loss of fluids during physical activity, but plain water can do this too. Keeping hydrated is important because dehydration greatly affects the ‘perception of effort’ experienced by an athlete. Dehydration also impairs mental function and may interfere with fine motor control and concentration and impair gastrointestinal function. So, it is more the other ingredients in sports drinks that mostly explain why they can benefit some athletes in certain situations.
First, let’s cover the carbohydrates. Sports drinks contain simple sugars or glucose polymers that help maintain hydration and blood glucose and enhance performance. Taking on extra carbohydrate in an easy to consumer drink is especially beneficial for strenuous endurance activities lasting longer than one hour and during intense activities or during prolonged competitive games that demand repeated intermittent activity.
Fluid transport to the tissues from beverages containing up to 8 per cent glucose is quite rapid. Most sports drinks contain carbohydrate in the 6 to 8 percent range which is much less than a standard soft drink. This is the ‘sweet spot’ (pun intend) where you see a fairly rapid glucose uptake in the body as more than 8 per cent may cause abdominal cramps, nausea and diarrhoea during intense activity. So, this class of sports drinks is called isotonic because the concentration of solutes in it is similar to that of human blood.
Hypotonic sports drinks are low in carbohydrate and are used more just for hydration. While hypertonic sports drinks are higher in carbohydrates by over 8% and are more for post-exercise refuelling, and as they are absorbed slower that’s why they’re not really suited for during exercise.
Taking on carbohydrates during exercise can support or enhance performance via two different mechanisms. The first is by providing extra fuel for the muscle, especially in endurance events. And the second mechanism is by a mouth sensing benefit to the brain and central nervous system. Just swilling carbohydrates in the mouth for 5 to 10 second is enough to stimulate reward centres in the brain to make the athlete feel better and reduce the perception of effect and enhancing pacing strategies. This mouth-sensing performance-enhancing effect of carbohydrates comes into play in shorter events of 45 to 75 minutes in duration.
The carbohydrate in sports drinks also contributes to their palatability which makes it more likely an athlete will drink. For athletes who prefer the flavours of sports drinks over water, it may be worth paying for the good taste to replace lost fluids.
As a side note there though, athletes who have short- or long-term goals related to body weight for either weight-restricted sports or where body weight to power ratio is important in their sport, then overuse of energy-dense fluids such as sports drinks may create problems for excess energy without a lot of long-term nutritional advantage.
The other key ingredient in sports drinks are electrolytes, sodium being the main one. Sodium makes up over half of our extracellular fluid so we do lose it from sweating so the theory is that sports drinks can help replace this. Most physically active people though do not need to replace the minerals lost in sweat immediately; a meal eaten within hours of competition replaces these minerals soon enough. Though some athletes who are particularly ‘salty sweaters’ may benefit more. The sodium in sports drinks also helps to increase the rate of fluid absorption from the GI tract and maintain plasma volume during activity and recovery.
The sodium content of sports drinks also encourages fluid intake by driving the thirst mechanism, while also increasing absorption and fluid retention. Sodium concentrations in the range of 10 to 25 mmol/L enhance the palatability and voluntary consumption of fluids consumed during exercise. Sports drinks with higher sodium concentrations are there to target the replacement of sweat electrolyte losses, with greater effects on fluid absorption and retention and may be more effective in the recovery phase after exercise.
Potassium is another electrolyte added to some drinks, but it likely has no real benefit considering most of our potassium is found inside the cell so sweat losses of it are very small. The same goes for magnesium which is found mostly inside the cells so adding this to a sports drink probably does very little, but it looks great to have it on the label!
A small number of sports drinks also include protein or amino acids at around 2 g per 100 mL. The case for consuming protein during exercise to enhance performance is pretty contentious with research appearing to mostly show benefits protein is taken on during sport in the face of sub-optimal intakes of carbohydrate. So, it is probably protein here that is just an extra energy source.
Then there are sports drinks that have added vitamins, and even herbal ingredients in them. This is a clear case of the company’s marketing department having been boozing way too much on at the marketing brainstorming session as these extra ingredients are seriously unlikely to offer any additional benefit. The only exception would be sports drinks that contain caffeine which can have performance benefits. Check out my prior podcast episode number 17 on how caffeine and its use in sport. A word of note though that doesn’t mean energy drinks like Red Bull are sports drinks – they have a much higher sugar content than isotonic sports drinks so will increase the risk of GI problems if you take them on during sport plus they’re carbonated so that’s another GI issue to deal with.
Sports drinks provide a convenient option for simultaneously addressing fuel, fluid and electrolyte needs before, during and after exercise. Before exercise, they keep the fluid and carbohydrate stores topped up. During exercise, they promote hydration and fuelling which is important in events over 90 minutes and reduced perception of effort in short-duration events. And post-exercise they can contribute to refuelling goals but here other foods and sports products should be considered to provide a more nutrient-dense approach to total recovery needs, though sports drinks could be convenient if there is limited time between training sessions or competition.
It is not all smooth sailing with sports drinks though as some athletes report that sports drinks cause gut discomfort or make them feel unwell. So, here, practising fluid intake strategies during training can assist in preventing dehydration as well as helping to overcome problems such as dislike of the taste, mouthfeel of the drink and gastrointestinal discomfort. The use of sports drinks with multiple transportable carbohydrates, typically a mixture of glucose and fructose, may assist helping too in maximising gastrointestinal comfort. Word of warning though, if you have FODMAP tolerance issues then these sorts of drinks will likely not be kind to your gut.
There is a really great fact sheet on sports drinks put together by the nutrition team at the AIS so I’ll link to that in the show notes. AIS https://www.ausport.gov.au/ais/nutrition/supplements/group_a/sports-foods2/sports-drink
Hydration index
As aside from talking about sports drinks and their effect on hydration, you will often hear that coffee and other caffeine-containing drinks will make you dehydrated. But how much truth is there to this claim? There is a small kernel of truth to claims that caffeine acts as a diuretic, but the key is the amount you have. Early research studies did find that caffeine causes water loss, but the amount of caffeine required is over 500 milligrams. That’s equal to 5 to 6 cups of coffee or an even greater number cups of tea.
Just as one example of the research into caffeine and hydration, 50 regular coffee drinkers had a range of tests to measure their hydration over 3 days. The hydration tests were repeated after they swapped their coffee for water for 3 days. Their food, fluid and exercise habits stayed constant. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084154
And after all that drinking and testing, the research team found no differences between the effect of caffeine or plain water on any measure of hydration. The participants were regular coffee drinkers so the result may have been different in people who consume little caffeine. But if someone drinks coffee rarely, then any effect on hydration will be fleeting.
With much interest in how different drinks can affect fluid balance, scientists have developed a ‘beverage hydration index’. The index ranks fluids by the balance between how much the body retains or loses fluid when compared against water over 4 hours. Using the beverage hydration index, there is little to separate coffee and plain water. And the same goes for cola, diet cola, tea, iced tea, orange juice and even sports drinks – they all can keep a person hydrated just as well as water. And I’ll link to this research on the hydration index study in the show notes. https://ajcn.nutrition.org/article/S0002-9165(22)06556-X/fulltext
Recipe
And finally as promised, if you’re looking at doing sports drinks on the cheap, here’s a homemade recipe you can use.
To about 80 to 100 mL of your favourite concentrated non-diet version of fruit cordial syrup flavour which is about 80% sugar undiluted (though check the label), add a quarter teaspoon of salt and make up to 1 litre. Job done. That quarter teaspoon of salt is about 1.5 grams of salt which equates to 600 mg of sodium so will give you a final sodium concentration in the drink of about 25 mmol/L. You can play around with the cordial flavour you use and amount of salt you add until you come up with your perfect mix – if it has the salty sweat taste like a Gatorade or Powerade then you know you’re on the mark.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.